• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a structural panel (200) comprising a front face and a rear face characterized in that it comprises: a. on its front face a plurality of two-dimensional acoustic black holes (210, 610) distributed on the surface of the panel in a network adapted to create a stop band for a frequency range below the lowest frequency dissipated by any one of two-dimensional acoustic black holes present on said panel; b. viscoelastic means (230, 630) connected to the panel and covering the edges of the two-dimensional acoustic black holes of said panel.
    公开号:FR3028906A1
    申请号:FR1461394
    申请日:2014-11-25
    公开日:2016-05-27
    发明作者:Francois Gautier；Sylvain Maugeais；Adrien Pelet；Omar Aklouche
    申请人:Universite du Maine；Institut de Recherche Technologique Jules Verne；University of Maine System；
    IPC主号:
    专利说明:

    [0001] The invention relates to a method and a device for vibratory damping of a panel. The invention is more particularly, but not exclusively, intended for damping the vibrations of a structural panel, in particular an automobile body panel, an aircraft fuselage panel or a machine tool cowling, without these examples being used. are exhaustive. Prior known solutions for limiting the vibrations of a panel and the propagation of vibrations by this panel, consist either of producing said panel in a material having intrinsic damping characteristics, or by the application on said panel of a specific coating. Also these solutions of the prior art lead overall to increase the mass of said panel equivalent mechanical performance. The phenomenon known as "acoustic black hole" is illustrated in FIG. 1A in the case of a blade in flexion. According to this theoretical example, said blade (100) comprises at one of its ends a thinning (110) progressive to zero thickness. The bending waves propagating in the blade (100) increase in amplitude and their wavelength is reduced by arriving in this thinned portion (110) until reaching a theoretically zero wavelength on the end of zero thickness, so that said waves do not reach said end which constitutes an anechoic termination. From a practical point of view, a zero thickness can not be reached and the actual end (111) of the blade is of finite thickness. This principle obtained according to a one-dimensional propagation of the waves is extended to a two-dimensional propagation by producing, Figure 1B, a pocket (120) of decreasing thickness towards its center to a hole (121) central. This device has the same limits as those relating to the blade, namely that the zero thickness can not be reached from a practical point of view on the edges of the hole. WO 2012/079158 discloses a practical example of using an acoustic black hole where the acoustic wave reflection effect on the non-zero thickness of the edges of the central hole is attenuated by a judicious sizing of the diameter of the central hole opposite the diameter of the pocket.
    [0002] The inventors have found that it is possible to obtain an effect equivalent to the theoretical effect of dissipation of an acoustic black hole with a termination of non-zero thickness, by bringing back a viscoelastic material, for example a piece of ribbon 3028906 2 adhesive at this end. However, the presence of an acoustic black hole in a panel is effective with respect to vibration damping only beyond a certain frequency, noted later, fi, so that this technical solution is not effective with respect to the 5 frequencies, called low frequencies, located in the audible spectrum. Throughout the text, the terms "two-dimensional acoustic black hole" designate a pocket of decreasing thickness towards its center pierced with a hole. The edges of said two-dimensional acoustic black hole are the edges of its hole, the diameter of said two-dimensional acoustic black hole is, for a circular black hole, the diameter of the pocket, i.e. the maximum diameter of the d-zone. degressive thickness. The invention aims to solve the disadvantages of the prior art and concerns for this purpose a structural panel comprising a front face and a rear face, which panel comprises: a. on its front face, a plurality of two-dimensional acoustic black holes distributed on the surface of the panel in a network capable of creating a stop band for a frequency range below the lowest frequency, fz, dissipated by any one of two-dimensional acoustic black holes present on said panel; b. the viscoelastic means connected to the panel and covering the edges of the two-dimensional acoustic black holes of said panel Thus the acoustic black holes taken individually ensure the damping of the vibrations beyond their limit frequency fii, z and their organization in pattern acts as a band rejection filter with respect to the lowest frequencies. The combination of the dimensions of the black holes and their distribution on the surface of the panel makes it possible to determine the frequency ranges thus filtered. This mode of damping is obtained by lightening the panel by the creation of two-dimensional acoustic black holes. The panel object of the invention consists of a metallic material or an organic matrix material, for example a composite material reinforced by cut fibers. In the latter case, the viscoelastic properties of the material constituting the panel allow, for certain applications, to obtain the technical effect without the addition of coating.
    [0003] The invention is advantageously implemented according to the embodiments described below which are to be considered individually or in any technically operative combination. According to one embodiment of the panel which is the subject of the invention, the viscoelastic means comprise a viscoelastic coating applied to the rear face of the panel, which coating obstructs the central bores of the two-dimensional black holes. Thus, said viscoelastic coating in addition to ensuring the damping of vibrations at the central endings, ensures the sealing of the panel.
    [0004] According to another embodiment, compatible with the previous one, the viscoelastic means comprise a paint applied on the front face of the panel. Thus the viscoelastic coating also ensures the protection of the panel vis-à-vis corrosion, as well as the appearance functions. According to a particular embodiment, the panel object of the invention comprises: c. a viscoelastic filling material filling the pockets of acoustic black holes. This embodiment makes it possible to obtain a uniform surface on the front face of the panel.
    [0005] Advantageously, the object panel of the invention comprises: d. a stiffener between two-dimensional acoustic black holes. Thus, said stiffener makes it possible to obtain increased rigidity and mechanical strength of the panel, without losing the damping effect of the acoustic black holes.
    [0006] According to a particular embodiment, the stiffener extends to the surface of the panel in a parabolic trace and a two-dimensional acoustic black hole is centered on the focus of said parabolic trace. Thus, a focusing effect of the vibrations towards acoustic black holes is obtained to increase the dissipative performance of the panel.
    [0007] Advantageously, the panel object of the invention comprises: e. a reinforcing panel plated on the rear face of the panel so as to take the viscoelastic coating sandwiched between the two 3028906 4 panels. Thus, the reinforcing panel makes it possible to improve both the tightness and the mechanical strength of the panel object of the invention. Advantageously, the decay profile of the thickness toward its center of each bidimensional acoustic black hole is a parabolic profile. This thickness variation profile makes it possible to obtain the most pronounced effect for a given dimension of the acoustic black hole. According to a particular embodiment, the periphery of the pocket of a two-dimensional acoustic black hole is circular and the diameter of the hole forming the edges of said black hole is between 1/20 'and 1/5' of the diameter of the periphery of the hole. the pocket. The invention also relates to a method for manufacturing a panel according to the invention, which method comprises the steps of: i. make the two-dimensional acoustic black holes on the front face by machining; Ii. realize the stiffener by additive manufacturing. This method of manufacture is particularly economical for small series where it allows to realize the panel in a minimum number of manufacturing steps. According to alternative methods, more suitable for medium or large series, the panel object of the invention is obtained by molding, thixoforming or injection of resin into a dry preform. The invention is explained below according to its preferred embodiments, in no way limiting, and with reference to FIGS. 1 to 6 in which: FIG. 1, relating to the prior art, shows FIG. 1A in a profile view an exemplary embodiment of an acoustic black hole at the end of a flexion plate, FIG. 1B in a cross-sectional profile view, an embodiment of a two-dimensional acoustic black hole; FIG. 2 represents, in a front view and a partial sectional view, an exemplary embodiment of a panel according to the invention comprising a plurality of acoustic black holes in a network; FIG. 3 shows, in FIG. 3A, a front view of an exemplary embodiment of a panel comprising a single acoustic black hole and FIG. 3B a diagram showing the effect of the acoustic black hole on the attenuation of the vibrations of said sign ; FIG. 4 illustrates examples of focusing realization of the effects of the acoustic black holes, FIG. 4A by the outline of the panel, FIG. 4B by the presence of a stiffener, and FIG. 4C illustrates the effect of these examples of FIG. focus on black hole efficiency; FIG. 5 is a diagram showing the influence of a plurality of acoustic black holes in a network on the attenuation of vibrations as a function of frequency; and FIG. 6 shows, in sectional sectional views, exemplary embodiments of a panel according to the invention comprising a reinforcement panel attached to its rear face. 2, according to an exemplary embodiment, the panel (200) which is the subject of the invention comprises a plurality of circular two-dimensional acoustic black holes (210) distributed on the surface of the panel according to a matrix array in a horizontal step (212) and a step (213) transverse. According to this embodiment, the horizontal pitch and the transverse pitch are substantially equal. Seen in section, the profile of each acoustic black hole (210) follows an evolution according to a variation in thickness represented by a polynomial of the second degree, decreasing from the periphery of the pocket to the edges of said acoustic black hole. The thickness on the edges of the acoustic black hole 20 is a function of technological criteria related to the method of producing said black hole and to the nature of the material constituting the panel. According to an exemplary embodiment, this thickness on the edges of the acoustic black hole is less than or equal to 1/10 'of the current thickness of the panel (200). According to this embodiment, the pocket of the acoustic black hole is circular around a diameter D, the central hole (211) 25 is of diameter d so that D / 20 <d <D / 5. According to this embodiment the panel comprises, on its rear face, a coating (230) consisting of a viscoelastic polymer. For example, said polymer is attached to the back of the panel by gluing. According to this exemplary embodiment, said viscoelastic polymer covers the entire rear face of the panel. Alternatively the viscoelastic polymer 30 is reported in the form of pellets covering the edges of the acoustic black holes. According to another embodiment, compatible with the preceding, the viscoelastic polymer is reported in the form of a paint layer on the front face or the rear face of the panel. The panel (200) is here represented rectangular outline, but said panel is likely to take any form of contour, depending on the intended application. According to exemplary embodiments, the panel (200) is made of a metallic material such as an aluminum alloy or a steel, or a composite material comprising a polymer matrix and a fibrous reinforcement. The pockets corresponding to the acoustic black holes are obtained by machining, for example by milling, or directly during the molding of the panel. For an acoustic black hole whose pocket is greater than 20 mm in diameter, the machining is advantageously performed in envelope machining in a helical cycle on a numerically controlled machine. For an acoustic black hole whose pocket diameter is less than 20 mm, the machining is advantageously performed according to a form work using, in plunge, a milling cutter whose profile corresponds to the desired thickness variation profile. For all the examples of implementation and exposed hereinafter the panel (200) consists of an aluminum alloy with a thickness h of 1.5 mm. The following examples are produced in order to highlight the synergistic effect obtained by the presence of a network of two-dimensional acoustic black holes compared to the presence of a black hole alone. These examples are made on flat panels, without this constituting a limitation of the invention. Example 1 - Unique Acoustic Black Hole 20 Figure 3A, according to a first illustrative example, a two-dimensional acoustic black hole (310) with a circular periphery of diameter D = 120 mm and a central hole (311) diameter of 10 mm is practiced. on a panel of 1 m2, any contour. The thickness of the edges of the acoustic black hole is of the order of 0.01 mm. Said panel is excited at a first point (341) by means of an impact hammer, and the vibratory response of the panel is measured at a second point (342) by means of an accelerometer. The impact hammer produces an impulse excitation whose spectrum corresponds to a flat spectrum over a frequency band of 10 Hz and 10 kHz. The response of the panel (300) comprising the two-dimensional acoustic black hole (310) is compared to the response of a control panel of identical geometry but without acoustic black hole. The curve (350) of FIG. 3B shows the efficiency (302), E [dB], of the acoustic black hole as a function of frequency. This plot is obtained by comparing the standard deviation Gy of the two responses: that, Gyp, of the panel (300) comprising the acoustic black hole (310), and that G'ef of the control panel, after applying a pass filter. band between the frequencies f, and f, corresponding to a range of 1/3 octave centered on the measurement frequency Nf.
    [0008] 5 E [dB] = 20.1og '(6'efl Gyp) Thus, an attenuation of the vibratory response of the panel by the presence of the acoustic black hole is counted positively on this diagram. FIG. 3B shows an example of efficiency (302), in dB, of the acoustic black hole as a function of frequency (301). Experimental results show that the two-dimensional acoustic black hole is effective in damping panel vibrations beyond a minimum frequency, denoted fh, which frequency corresponds empirically to a flexural wavelength, λ, in the panel, the order of magnitude of the pocket radius of the two-dimensional acoustic black hole is: = 2D / 3 Which in terms of frequency results in the relation: ## EQU1 ## Young of the material constituting the panel; - h: thickness of the panel; Y: Poisson's ratio of the material constituting the panel; p: density of the material constituting the panel. Thus, in the present case, for an acoustic black hole with a diameter of 120 mm, = 2744 Hz. In order to be effective at average audible frequencies, of the order of 500 Hz it is necessary, having use of a single two-dimensional acoustic black hole, that it reaches a diameter of the order of 280 mm, which is important with regard to the size of the panel on the one hand, and other by only produces one limited attenuation, less than 3 dB, at this frequency. The following table gives examples of fii, z values for different acoustic black hole diameters in an aluminum alloy panel with a thickness of 1.5 mm. Diameter [mm] fi. [Hz] 60 10976 120 2744 280 504 Example 2 - Improvement of performance by focusing Figure 4, the efficiency of a two-dimensional acoustic black hole is improved by placing it judiciously opposite the geometry of the panel. 4A, according to a first example, the panel (401) is no longer any contour but elliptical contour, the two-dimensional acoustic black hole (411) being placed at one of the ellipse focal points, this mode of However, realization requires a particular outline of the panel, which must be compatible insertion of the panel in a mechanical assembly. 4B, according to another example, the panel is of any contour but includes a stiffener (420) describing a parabolic trace on the surface of the panel (402), the two-dimensional acoustic black hole (412) being placed at the focus of said dish . Such a stiffener (420) is for example attached to the panel (402) by welding, coking or additive manufacturing depending on the nature of the material constituting the panel and the importance of the series of manufacture.
    [0009] FIG. 4C compares the response (452) of the stiffener panel and the control panel response (350) to show that the arrangements focusing the bending waves toward the black hole tend to increase the efficiency of said black hole. However, it is not possible to significantly reduce the value of Example 3 - Network black acoustic holes 25 According to the example of FIG. 5, the panel comprises on its first face a matrix array of 60 black acoustic holes, the circular periphery of the pocket is 60 mm in diameter, the centers of said acoustic black holes being spaced 90 mm apart. The comparison of the acoustic efficiency (550) of this configuration with respect to the other solutions, with a single black hole (350) and a single black hole with focusing of the effect by means of a stiffener (452), shows that networked acoustic black holes at the same time make it possible to increase the efficiency of nearly 10 dB beyond the frequency f 1. a black hole taken individually and especially to extend this efficiency below the frequency f ,,, 2. Without being bound by any theory, it is found that the acoustic black holes thus placed in a network make it possible to be effective from a wavelength substantially equal to the distribution pitch of said acoustic black holes on the surface of the panel. Thus, in order to obtain effective attenuation at low frequency, it is possible to use an array of acoustic black holes whose pockets are of small diameter, distributed in a wide pitch on the panel. The individual efficiency of each or a portion of said black holes is, according to an exemplary embodiment improved by the judicious placement of stiffeners. The use of small diameter two-dimensional acoustic black holes makes it possible to achieve these very quickly by machining. The panel retains structural capabilities. 6A, according to an exemplary embodiment of the panel object of the invention, it is of composite structure and comprises a first layer (601) structural consisting of a panel, for example metallic, having on its front face a network of holes two-dimensional acoustic blacks (610), a layer (630) made of a viscoelastic polymer plated on the back side of the first (601) layer and sandwiched by a third structural layer (602) made of, for example, a material metallic. According to an alternative constitution, one or both of the structural layers (601, 602) consist of a composite material of polymer matrix and fibrous reinforcement.
    [0010] Figure 6B, according to a variant of this latter embodiment, the third layer (604) also comprises an array of acoustic black holes (611). 6C, according to another embodiment, compatible with the previous ones, the acoustic black holes are filled by a viscoelastic filling material (620). This filler material contributes to the damping and the anechoic dissipation of the vibrations and makes it possible to obtain a uniform surface on the first face of the panel which is the subject of the invention. The above description and the exemplary embodiments show that the invention achieves the desired objectives, in particular it makes it possible to obtain damping of the vibrations in the audible frequency bands, more particularly in the medium and low frequency, by reducing the panel. These acoustic characteristics are advantageously combined with pockets and local thinning used, especially in the aeronautical field to lighten the panels.
    权利要求:
    Claims (7)
    [0001]
    REVENDICATIONS1. Structural panel (200) comprising a front face and a rear face characterized in that it comprises: a. on its front face a plurality of two-dimensional acoustic black holes (210, 610) distributed on the surface of the panel in a network adapted to create a stop band for a frequency range below the lowest frequency dissipated by any one of two-dimensional acoustic black holes present on said panel; b. viscoelastic means (230, 630) connected to the panel and covering the edges of the two-dimensional acoustic black holes of said panel.
    [0002]
    2. Panel according to claim 1, wherein the viscoelastic means comprise a viscoelastic coating (230) applied on the rear face of the panel which coating obstructs the central bores (211) of two-dimensional black holes.
    [0003]
    The structural panel of claim 1 or claim 2, wherein the viscoelastic means comprises a paint applied to the front face of the panel.
    [0004]
    4. Panel according to any one of claims 1 to 3, comprising: c. a viscoelastic filling material (620) filling the pockets of the acoustic black holes.
    [0005]
    5. Panel according to any one of claims 1 to 4, comprising: d. a stiffener (420) extending between two-dimensional acoustic black holes.
    [0006]
    The panel of claim 5, wherein the stiffener (420) extends to the panel surface in a parabolic trace and a two-dimensional acoustic black hole is centered on the focus of said trace 3028906
    [0007]
    A parabolic panel according to any one of claims 2 to 6, comprising: e. a reinforcing panel (602, 604) plated on the back side of the panel to take the viscoelastic coating (630) sandwiched between the two panels (601, 602, 60). The panel of claims 1-7, wherein the decay profile of the thickness toward its center of each bidimensional acoustic black hole is a parabolic profile. Panel according to claims 1 to 8, wherein the periphery of the pocket of a bidmensional acoustic black hole is circular and that the diameter, d, of the hole (211) forming the edges of said black hole is between 1/20 th and 1/5 th of the diameter, D, of the periphery of the pocket. A panel as claimed in any one of the preceding claims, consisting of a metal material. A panel according to any one of claims 1 to 9, consisting of a polymer matrix material. A process for manufacturing a panel according to claim 5, characterized in that it comprises the steps of: i. make the two-dimensional acoustic black holes on the front face by machining; ii. realize the stiffener by additive manufacturing.
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    同族专利:
    公开号 | 公开日
    FR3028906B1|2020-02-07|
    引用文献:
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    FR2289993A1|1974-10-29|1976-05-28|Busnel Rene|SOUND ABSORPTION DEVICE|
    EP1020846A2|1999-01-14|2000-07-19|Nichias Corporation|Sound absorbing structure|
    EP2487677A1|2010-01-08|2012-08-15|Institute Of Acoustics, Chinese Academy Of Science|Compound sound absorption device with built-in resonant cavity|
    EP2578802A1|2010-05-24|2013-04-10|IHI Corporation|Vibration damping blade for fluid|
    US20140339014A1|2013-05-17|2014-11-20|Purdue Research Foundation|Sound barrier systems|CN108122551A|2017-12-20|2018-06-05|南京航空航天大学|A kind of acoustics black hole vibration absorber|
    CN108133700A|2017-12-20|2018-06-08|南京航空航天大学|A kind of acoustics black hole vibration and noise reducing device|
    WO2019148891A1|2018-01-30|2019-08-08|香港理工大学|Wideband vibration suppression device utilizing properties of sonic black hole|
    CN112497863A|2021-01-29|2021-03-16|北京市劳动保护科学研究所|Sound insulation brick and sound insulation device|
    法律状态:
    2015-11-23| PLFP| Fee payment|Year of fee payment: 2 |
    2016-05-27| PLSC| Search report ready|Effective date: 20160527 |
    2016-11-29| PLFP| Fee payment|Year of fee payment: 3 |
    2017-11-30| PLFP| Fee payment|Year of fee payment: 4 |
    2018-11-30| PLFP| Fee payment|Year of fee payment: 5 |
    2019-11-29| PLFP| Fee payment|Year of fee payment: 6 |
    2020-11-30| PLFP| Fee payment|Year of fee payment: 7 |
    2021-09-21| PLFP| Fee payment|Year of fee payment: 8 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1461394|2014-11-25|
    FR1461394A|FR3028906B1|2014-11-25|2014-11-25|METHOD AND DEVICE FOR VIBRATORY DAMPING OF A PANEL|FR1461394A| FR3028906B1|2014-11-25|2014-11-25|METHOD AND DEVICE FOR VIBRATORY DAMPING OF A PANEL|
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